Diseases

Rhizopus Head Rot of Sunflower

Helianthus annuus L.

A disease of sunflower heads caused by fungi of the genus Rhizopus, characterized by rapid moisture loss and mummification of tissues, with felt-like mycelium forming between the seeds.

In the reference 55 varieties crop Sunflower, where this is mentioned in the description.

The pathogens of the disease are fungi of the order Mucorales, primarily the species Rhizopus stolonifer, Rhizopus nodosus, Rhizopus oryzae, and Rhizopus arrhizus. The disease manifests during the head maturation period, starting with the appearance of brown, decaying spots on the back side, which spread rapidly.

Distinctive signs of the infection include rapid moisture loss leading to hardening and mummification of tissues, as well as the development of gray or dirty-white felt-like mycelium between the seeds on the front side of the head. Affected seeds become shriveled, acquire a bitter taste, and are prone to shattering.

Pathogen development is favored by high temperatures in the range of 30–35 °C combined with low air humidity. The pathogens have a wide host range and do not exhibit narrow race specificity; currently, there are no recognized specific resistance genes to this disease.

General information about the subject — on the page Dry rot.

Sources8

Varieties of Sunflower mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.